How to Hang a Mirror on a Tiled Wall: Checks Before You Drill

To hang a mirror on a tiled wall, find out what is behind the tile first, put both fixing holes at least 20mm inside a tile face and never in a grout line, drill the tile on rotary only with a tile bit, then fit the fixing the wall behind needs: a screw into a stud, a plug in masonry, or a toggle through the lining. If the wall is inside a shower or the tiles are mosaic, do not drill it. Lean the mirror or use another wall. We worked out where a pair of holes lands on the nine tile layouts you see in New Zealand bathrooms, how long the screw has to be once the tile and adhesive are in the way, and which of our mirrors a tiled wall can carry.

This guide covers the tile layer only: what changes because there is a tile in the way. Once you are through it, the wall behind is one of three we have already written up. Our plasterboard guide covers studs, toggles and how much a lining will hold. Our concrete and brick guide covers plugs and hammer drills. And if drilling is off the table, the no drill options are there, with the honest limits on adhesive.

What a tiled wall is made of

A tiled wall is a sandwich, and only the back of it can hold a mirror. On the face is the tile: a glazed ceramic wall tile is usually 6 to 8mm thick, a porcelain or large format tile 8 to 12mm. Behind it is the adhesive bed, 2 to 5mm. Behind that is the part that matters. In a timber framed New Zealand home that is a wet area plasterboard, most often GIB Aqualine in 10mm or 13mm, which GIB describes as the lining made for areas covered by the Building Code clause on internal moisture and a suitable substrate for tiles on timber framing; some bathrooms use a fibre cement sheet of 6 or 9mm instead. Either sits on studs, usually at 600mm centres and sometimes 400. In apartments and in a lot of 1960s to 1980s homes the wall behind the tile is concrete block or precast concrete, with the tile bonded straight to it or to a render coat. In older villas and bungalows, tiles can sit on fibrous plaster or hardboard, often only to dado height, and that is the weakest wall of the lot.

Thicknesses are the common range in New Zealand bathrooms, not a standard. If you can see the edge of the tiling at a trim, a window reveal or behind a removed fitting, measure yours.

Add the tile and the adhesive together and you get what we call the dead zone: 8 to 17mm of wall that contributes nothing. Every number later in this guide starts by adding that dead zone to whatever the fixing would need on a bare wall.

How to tell what is behind your tiles

Tap the wall with a knuckle. A hollow, slightly drummy ring is a lining on studs; a dull thud that does not change as you move along is masonry. Then look for an existing fixing: the screws behind a towel rail bracket, a toilet roll holder, or the fixings holding the vanity to the wall. Back one out and the hole shows you the layers, green faced board, grey cement sheet, or grey block dust. Stud finders struggle through dense tile and adhesive, so if the wall next door is plasterboard, find the stud line on that wall and carry it through the corner with a tape; studs are 400 or 600mm apart and there is always one at a corner. Finally, run a cable and pipe detector over the area. The vanity wall carries the water pipes rising to the basin, and the light switch and the cable to a mirror light usually run straight up from the switch.

Three checks before you drill

1. Is this wall part of the shower?

Tiled showers in New Zealand are built to the Building Code acceptable solution for internal moisture, which BRANZ summarises as: all shower wall and floor finishes must be impervious, a waterproof membrane must be installed behind and underneath shower tiling (the only exception being a polished concrete substrate), the enclosure walls run to at least 1800mm above the floor, and every penetration must be sealed. A tiled shower also needs a building consent. None of that is written with a mirror in mind, which is the point: a screw hole inside the shower enclosure, or over a bath that has a shower above it, goes through the membrane that keeps the framing dry, and nothing you do with a plug fixes that. Put the mirror on the vanity wall, or on a dry wall, and leave the shower alone. Basin splashes are not a shower; the vanity wall is the normal place for a bathroom mirror and the one this guide is written for.

2. What is behind the tile?

Use the tap, the existing fixing and the detector from the section above. The answer decides the fixing: a stud, a toggle through the lining, or a plug in masonry. If the wall is tiles on fibrous plaster or hardboard, treat it as the weakest plasterboard and keep to the lighter mirrors, or lean.

3. How heavy is the mirror, and where are its hooks?

Turn the mirror over and measure three things: the distance between the two hooks, the drop from the top edge of the mirror to the hook, and the weight from the product page. Those three numbers decide where the holes go and how far apart. Here is the hardware on the back of our own mirrors.

Hook positions can vary a little between batches. Measure your own mirror rather than trusting a photo, and give each hook its own screw so the mirror cannot swing off level.

Where the holes can go: the 20mm rule

A glazed tile is strongest in the middle of its body and weakest at its edges, where the body has nothing beside it to spread the load and the glaze meets the grout. Grout is softer than the tile, crumbles around a plug, and in a bathroom it is the path water takes into the adhesive bed. So two rules. Never drill a grout line. And keep the centre of every hole at least 20mm inside the face of the tile, which puts the edge of a 6mm hole 17mm from the joint.

With one hole that is easy. With two it is not, because the second hole lands wherever the mirror's hooks put it, not where you would like. So we did the sum for the tile layouts common in New Zealand bathrooms: for every possible position of the first hole across a tile and a joint, we checked whether both holes of a pair sat inside a tile face, using the hook spacing on our own mirrors. The table gives the share of positions that work first time, and what to do when yours does not. The pair is assumed to be at one height, which is how every mirror in this guide hangs.

Computed with a 3mm grout joint and a 20mm keep out from every edge, for every 1mm position of the first hole across one tile and one joint, both holes at one height. A 2mm rectified joint changes the figures by about one point. The Zenith X at 67cm apart sits within a point or two of the Titan on every layout except the finger tile, where it drops to 4%.

Read it as a rule of thumb. On any tile 300mm or bigger in both directions, hang the mirror where you want it and expect a move of at most 2cm up or down, occasionally 4cm sideways. On a 200 x 100 subway wall, plan on moving. On anything under 100mm in either direction, the maths says you will be placing the mirror to suit the tiles rather than the basin, and under 75mm you should not be drilling at all.

Mark it out

1. Measure the hook spacing and the drop from the top edge to the hook on your mirror. Decide the height of the top edge: above a vanity, 15 to 30cm of clear tile between the benchtop and the frame reads right, and our round mirror guide sizes a circle to the vanity beneath it.
2. Subtract the drop from the top edge height to get the hole height. Run a level line of masking tape across the wall at that height and mark both hole points on it, the hook spacing apart and centred on the basin.
3. Check each mark against the grid: at least 20mm from every edge of its tile, and not in a joint. If one fails, move both marks together, up or down by up to 2cm first, because that keeps the mirror centred; then sideways if you must. Both holes stay in the same row of tiles.
4. Measure the spacing again after the move, and check the line is level. A few millimetres of error across 90cm shows.
5. Wrap tape round the drill bit at the depth of the dead zone, 8 to 17mm, so you can feel and see when you are through the tile and into the wall.

If you have a round mirror, the paper template method in our round mirror hanging guide transfers the hook points without guesswork, and if you are hanging two mirrors side by side, the level line method in our two mirror installation guide applies unchanged on tile.

The fixing behind the tile

One rule for all three walls: the fixing has to grip the structure, never the tile. A plug that stops inside the tile expands inside the tile when the screw goes in, and that is the classic cracked tile a week after the mirror went up. Add the dead zone to everything.

Lengths are tile plus adhesive plus lining plus the embedment above, rounded up to a stock screw. Fixings makers publish their own drill depths; use theirs where they differ.

How much a toggle will hold is the question our plasterboard and large wall mirror guides already answer: around 8 to 10kg per good fastener in standard board, about a quarter more in 13mm wet area board, and a stud carries far more than either. That is the whole product decision on a tiled framed wall. The Aure, Le Vue and Lyra put 4 to 6kg on each fixing, so a pair of good toggles through wet area board carries them with room to spare. The Titan and Zenith X put 9.5kg on each, which is the limit of a toggle before the board face gives, so they go into a stud or masonry, or they lean. Both ship with a stand, and our leaning mirror guide covers the restraint.

One more step in any bathroom wall: before the plug or screw goes in, put a bead of neutral cure silicone into the hole. BRANZ's point about sealing every penetration is written for the membrane zone, but on the vanity wall it is cheap insurance against steam and splashes finding their way into the lining.

Drilling the tile, step by step

The technique is the same one Bunnings New Zealand gives for tiles: a tile or masonry bit for ceramic, a diamond bit for porcelain, masking tape on the spot, low speed, gentle pressure, and water to keep the bit cool. Here it is with the mirror in mind.

1. Pick the bit. A carbide spear point tile bit for ceramic. A diamond tipped or diamond core bit for porcelain, which is harder and will burn a carbide tip out. If you do not know which you have, use the diamond bit: it cuts both, it just takes longer on ceramic.
2. Put a cross of masking tape over each mark and remark the point on the tape. The tape stops the bit skating across the glaze.
3. Rotary only. Turn hammer action off and leave it off until the bit is through the tile. Start slow, with light, steady pressure. With a round diamond bit, start at a slight angle to cut a crescent, then bring the drill upright.
4. Keep the bit cool. Dip it in water every few seconds, or hold a wet sponge against the tile. Porcelain can take a minute or more per hole; let the bit do the work.
5. Feel for the breakthrough. The resistance drops as the bit leaves the tile and enters the adhesive and the board; that is your tape mark on the bit. Stop. Now change to the fixing the wall needs: a pilot into the stud, a masonry bit with hammer on into block, or the core bit for a toggle hole.
6. Vacuum the hole, run a bead of silicone in, and fit the plug or drive the screw, leaving the head 4 to 5mm proud for a keyhole or bracket, or fit a hook for a D ring.
7. Hang the mirror, pull down gently on it, and check it is level. Clean the tape residue off the glaze with a damp cloth.

Common mistakes on tile

• Hammer action through the tile. It cracks the glaze or the tile outright. Hammer only in masonry, and only once the bit is in it.
• A plug that stops in the tile. The screw expands it inside the tile and the tile cracks later. Drill deep enough and push the plug past the dead zone.
• Drilling the grout line because it looks easier. It is softer, so it feels easier, and then the plug spins in it and water follows the screw in.
• A self drilling plasterboard anchor. Made for bare board, stopped dead by tile. Use a toggle through a cored hole instead.
• Trusting a stud finder through tile. Carry the stud line through from the neighbouring wall, or use an existing fixing to see what is there.
• Drilling the shower wall. The membrane behind it is the one layer in the house you cannot patch from the front.

Which of our mirrors suit a tiled wall

Two bathroom notes that are not about fixings. Our silvering guide explains why steam and salt air attack a mirror's edges first, which is an argument for a well ventilated room and a sealed backing. And our safety glass guide explains why a framed mirror hung on the wall is furniture under the glazing rules, while a mirror panel fixed into the wall of a wet area is not.

When not to drill at all

Four cases where the right answer is a different wall or a leaning mirror: the wall is inside the shower enclosure or over a bath with a shower; the tiles are mosaic or finger tiles under 100mm, where the sum above leaves no safe body; the tiles sit on fibrous plaster or hardboard in an older home and crumble around a fixing; or you rent, or share a wall with a neighbour in an apartment, and the body corporate rules or the tenancy do not allow holes. In each case our leaning mirror guide covers the restraint, and the no drill guide is honest about what adhesive will and will not carry on a smooth tile.

Frequently asked questions